China cannot buy ASML machines. All advanced semiconductor manufacturing in China is done with stockpiled ASML machines from before the ban.
SK Hynix also has significant memory manufacturing presence in China; or about 40% of the company's entire DRAM capacity.
Of course the problem is we don't see what would be missed by doing this investment. If you put extra people into solving this problem that means less people curing cancer or whatever. (China has a lot of people, but not unlimited)